This invention relates generally to fluorescence spectroscopy and, more particularly, to a fluorescene spectrophotometer designed to measure polarized fluorescent light.
A fluorescene spectrophotometer generally comprises a light source, a primary or excitation monochromator, a sample cell containing a sample to be analyzed, a secondary or emission monochromator, a photodetector, and a signal processing device. The excitation monochromator selects a specific wavelength of the light from the light source and projects it onto the sample in the cell. The resultant fluorescene is introduced into the emission monochromator and a fluorescent light of a selected wavelength is directed onto the photodetector, which produces an electrical signal corresponding to the intensity of the fluorescent light.
To measure the degree of polarization of fluorescent light by a fluorescence spectrophotometer it has been customary to place a polarizer in the path of excitation light from the excitation monochromator to the sample and another polarizer in the path of fluorescence from the sample to the emission monochromator. In the prior art method of measuring the degree of polarization of fluorescent light, a sample is stained with a single kind of fluorescent dye to measure the degree of polarization of fluorescent light of a single wavelength. For example, in biotechnology by measuring the degree of polarization of a fluorescent light emitted by a cell stained with a fluorescent dye it is possible to know the fluidity of the membrane of the cell.
With recent advancement of biotechnology it has become necessary to measure the degree of polarization of the polarized fluorescent light from different parts of a single cell, such as the surface of the membrane of a cell or the interior thereof.
It is possible to stain different parts of a cell with different dyes. However, there are no fluorescene spectrophotometers available which can measure the time course of polarization of fluorescent light as well as the degree of polarization of the fluorescene of different wavelengths emitted by the same sample.
Accordingly, the primary object of the invention is to provide a fluorescene spectrophotometer which can measure the time course of polarized fluorescent light of more that two wavelengths emitted by a sample stained with more than two kinds of fluorescent dyes.